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Topic: ColorChecker passport, what's wrong? (Read 28538 times)

I have similar problem with CCP. I even replace the different one, but it turns out the monitor profile is dated. The CCP software does use the monitor profile when creating the profile. How long ago has you calibrated your monitor?

Recalibrate every two weeks, and the profile is updated and rebuild ever 5 minutes..

First, the Passport is an excellent small and portable chart for field use.

But the DNG profiling software simultaneously sucks and blows, and that's not a compliment.

The first half of the problem is the DNG profiling software's fault: it only uses the classic 24 patches when building profiles; it completely ignores those other 26 patches. Considering that those other patches include both some much-more-saturated patches that really help define the camera's response as well as a number of near-neutral patches that really help nail down where the neutral axis (and therefore white balance) lies, that omission is both incomprehensible and inexcusable.

The second half is Adobe's fault, and that's the incoherent mess that is the DNG color "profiling" process. It's not even remotely theoretically possible to get anything vaguely resembling colorimetric accuracy from DNG profiles, though you can fake it by manually tweaking a DNG profile to be as close as you can get it and then build an ICC profile on top of it. Basically, if your idea of "good" or "pleasing" color means no-holds-barred impressionistic interpretations of color, DNG is for you. But if you want an accurate representation of color, DNG is a cruel and unusual tool for extraordinary rendition.

If you care about accurate color, you simply cannot use Adobe products to develop your raw files. Nor can you use many of the other popular raw development engines, such as Canon's DPP, because they suffer from the same root problem: the programmers have decided that their taste in color palettes is best for you. Accurate color, hell -- you can't even stop any of these raw developers from applying a contrast-boosting (and detail-obliterating) S-curve!

It's a real shame, too, because the hardware itself is quite readily capable of superbly accurate color reproduction. There's no reason why accurate color shouldn't be the default starting position, always available as an option, with the various "secret sauce" recipes only optionally added on top.

So what you're left with is mostly tools that come from the Free / Open Source software crowd, some of which produce superlative results but none of which have user interfaces with the spit-n-polish that Adobe products have. That is, you can use Adobe (etc.) products which are beautiful to look at but which mangle your own images, or you can use other tools that are ugly to look at but which make your own images shine.

If you go that route, you'll want something which is at least loosely based on dcraw for its development engine. My own runaway favorite is Raw Photo Processor, but there are other good options.

And your basic workflow would be to first create high quality quasi-generic ICC profiles in carefully controlled situations. The ColorChecker Passport, as useful as it is in the field, really doesn't have enough patches for that kind of work. There are other charts available for purchase that are usable, but I personally made my own chart; it has a replica of the classic 24 ColorChecker patches, another couple dozen paints, a black trap, some PTFE thread tape, a dozen or so wood chips, and a couple hundred patches printed on an iPF8100. I have some plans for a second version, but it's served me well.

Of course, you'll need a spectrophotometer to build the necessary reference files for any chart; there's enough batch-to-batch variation with any manufacturing process that you'll want to measure your actual chart, even if you buy it from a reputable source. The i1 Pro is an excellent tool for this purpose.

You'll also need software that lets you build these kinds of profiles. X-Rite doesn't include that with the software they bundle with their consumer-level instruments, but they do sell some very good and very expensive software that would work. However, if you're not afraid of the command line, ArgyllCMS produces absolutely amazing results, is free, and is superbly supported by the author on a mailing list.

So, you'd build profiles for each camera with the light sources you most care about; one for each of the camera's pre-canned white balance settings is a pretty good idea. And you might even want to consider building one such profile for each lens, as different lenses have different color characteristics.

Then, when you're shooting, you'd include a shot of the Passport as usual. When you get back to the studio, you'd do a linear gamma UNIWB development of that shot -- basically, just dump the raw file completely unmodified to a TIFF. You'd build a matrix profile from that and do a reverse lookup of D50 white, which will tell you what per-channel multipliers you need both for white balance and to normalize exposure. You'd then use those figures when developing the real shots and apply your most-appropriate custom-built pre-canned ICC profile.

That'll get you as close to perfect color as you're going to get with a DSLR. And, indeed, said color is good enough that, if you've got a similar workflow at the printing end of things, you can make copies of artwork such that the artist herself has to stare a long time at the original and copy side-by-side to be able to spot the differences -- the gamuts of the original and your printer permitting, of course.

One other note...you're having problems with reds and you're mentioning problems with overexposure. Some cameras, especially older ones, are notorious for overexposing reds, especially reds rich in infrared such as flower petals in sunlight. It's impossible to recover an overexposed image, no matter how good your profiling software.

What you can do, however, is underexpose the image sufficiently to prevent the reds from blowing, and still use the Passport to determine how to normalize the white balance and exposure in post. You're essentially applying digital ISO boost in post-production at that point so you have to be careful of noise, but you can boost a 5DIII ISO 100 exposure by a half-dozen stops in post if you're careful so it's not as much of a concern as it used to be.

But for me I'm not looking to have 110% rightColor for everything. The reason I liked the Cc was that it made everything south better looking than what came out, or rather how Lightroom would make my colors look. This was with the 5d2. And now also with the 1dx the profile I got with flash is good enough for me. I'm only trying to get the results I got with the 5d2 with the 1dx and am a bit frustrated that it seems so hard to get even remotely okay reds.

Even more so when you explain the camera itself has no problem with it, and actually, the colors on my camera screen lpoks mucg more like the real world thAn the profiled ones, something isnt right..

Then, in that case, I'd suggest a simplified version of what I described.

First, don't create DNG profiles on the fly for every shot. Instead, create a few carefully-constructed DNG profiles for the types of lighting conditions you care about. Pay particular attention to getting the chart evenly illuminated and avoiding anything that might reflect a color cast onto the chart. A light tent is great for this sort of thing.

When you shoot, still shoot the Passport. First, if you ever do go to a more refined workflow, you'll be able to use that image of the Passport as I described. But, more immediately, you can eyeball / eyedropper the passport to get the proper white balance and exposure much better than you can a simple gray card.

First -- after, of course, selecting your pre-canned DNG profile -- crop the shot to just the Passport. Then, set a preliminary white balance with the eyedropper on the gray patch next to the yellow patch. Now, adjust exposure until, by the numbers, the neutral patches are as close as you can reasonably get them, paying more attention to the midtones than the shadows and highlights (both of which are going to get mutilated with Adobe's rendering engine whether you want them to or not). If nothing else, get the N5 patch to read close to 118/118/118. Then, crank the saturation as high as it will go and fiddle with the white balance until the Passport looks as close to normal as you can. Return the saturation to normal, and double-check that the exposure is still where it should be. If not, repeat both exposure and white balance adjustments. When done, and only when done, you can then move on to the creative adjustments (if you're so inclined).

And don't forget that you're never going to get correct color with clipped highlights...and that Adobe's tools do all sorts of hidden black magic to protect you from clipped highlights so you may well not be aware that they're clipped. There are lots of free tools that'll help you analyze raw files; run your problem images through one or two of them to see if there's any clipping in the raw files themselves.

And...one more thought.

All the working spaces, even Lab, have limited color gamuts. It could well be that the raw data isn't clipped but that the colors lie outside of your working space -- let alone your monitor's or printer's color spaces. Try again with ProPhoto, which has all sorts of problems but at least encompasses all output devices you'll be able to work with. Even if that solves the immediate clipping problem, your troubles aren't over...you're still probably not going to be able to output that color, either on your display or in print, and now you've got to deal with Adobe's substantially suboptimal profile conversion routines and hope that their perceptual rendering doesn't just wind up clipping the colors anyway.

For the vast majority of people, including some of us who also shoot colour critical artwork for money, the Passport and an Adobe workflow is more than up to the task.

The real issue here has been touched on, but not presented as the actual problem. Overexposure of the red channel. One blown channel will not show "blinkies", well it doesn't on my camera, in this kind of situation all you need to do is go to your info button on playback and scroll through to channel histograms, expose to keep the red channel from clipping then lift exposure slider in post, job done.

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Too often we lose sight of the fact that photography is about capturing light, if we have the ability to take control of that light then we grow exponentially as photographers. More often than not the image is not about lens speed, sensor size, DR, MP's or AF, it is about the light.

The Swedish Photographer ASSOCIATION did a test of different reference card and software, best was QP-Card

You keep flogging the QPcard. Honestly, it's not all that impressive. A mere 35 patches to begin with...and then they cluster all the patches in small clumps in device space, effectively wasting over half of the patches. A more uniform distribution in device space would produce far better profiling results as you'd sample a much larger portion of device space.

That's what the Passport does. The classic 24 patches are already pretty well distributed in device space. Then you've got all those saturated patches that probe the boundaries of device space; the QPcard doesn't have any saturated patches, meaning it's just sampling the center of device space.

And then the Passport has a number of near-neutral patches that they market for the purposes of creative white balance, but which actually provide tight clustered sampling around the neutral axis, which is perfect for triangulating white balance and one of the two times you're really at an advantage for multiple sample points in a small space when building generic profiles for a device with unknown characteristics. The other, of course, is for neutral points at the extremes of the dynamic range so you can closely probe the shadow and highlight portions of the response curves -- and, hey-presto, the Passport has those patches as well!

Now, might the QPcard DNG profile-building software suck less than the Passport DNG profile-building software? No clue. Don't care. DNG profiles are worthless, sorry jokes when it comes to color management; by the specification's very design and stated intentions, you're never going to get anything close to accurate color out of them. They're meant for "pleasing" color -- and "pleasing," by definition in this case, is in the eye of the software developer writing the profile-building code. And "pleasing" on said software developer's own monitor in said software developer's own office, neither of which is likely to be set up for color critical work.

And, similarly, you're never going to build a quality LUT input profile with a target with only 35 patches -- and not even with the mere 50 patches of the Passport. You need at least a few times as many patches for critical work, and you're just not going to get that in a small, portable target.

But that small, portable target can get you a high-quality matrix profile that you either use to set white balance and exposure or that you apply before applying your studio-created large-patch-count LUT profile.

And, for that, the Passport is very significantly superior to the QPcard. Dramatically so.

What do you mean, Pro Photo can reproduce all colors without clipping and you can then proof in ProPhoto color space into a smaller profile/color space as Adobe RGB and then convert to Adobe RGB with good results

If you want a much more useful working space, try BetaRGB. No imaginary colors, encompasses all of AdobeRGB, encompasses most of all real-world output devices (which AdobeRGB doesn't), and otherwise very intelligently designed.

What do I know about color? Not much, granted -- especially in comparison with true digital color scientists such as Graeme Gill and Bruce Lindbloom. But I know a hell of a lot more than whoever wrote that page you link to, which has real doozies like this on it:

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Manual white balancing, using a neutral gray target in the scene, is the best way to achieve neutral grays in the picture. However, it doesn't matter if the gray target is manufactured by Kodak, Datacolor, X-rite or QPcard; the end result is the same.

First, using a chart with a single gray patch on it to achieve gray balance is, by definition, the worst possible empirical method for the task. A chart with two gray patches is much superior, and a full-sized color chart is ideal.

Second, the notion that the manufacturer doesn't matter and that all produce the same results is ludicrous. If you are going to use the click method, the uniformity of the spectral reflectivity of the target is paramount, and none of the targets on the market are as spectrally uniform as even a styrofoam coffee cup. (Well, with one notable exception: anything from LabSphere made of Spectralon. But those targets cost as much as an L lens.) I know -- I've got many of them and I've measured many of the rest with a spectrophotometer. I've actually got a can of paint from Home Depot that's much better than average, thanks to a helpful response to a query I made to their technical support group.

Anyway, that's just the easy and trivially obvious misinformation on that page. They also suffer from misconceptions such as this:

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The color samples are divided into four groups. The primary groups have 9 saturated samples of red, green and blue picked to accurately determine the spectral midpoints of the on-sensor filters.

It's a nice-sounding idea, but completely worthless. Neither ICC nor DNG profiles give a damn what the spectral midpoints of the filters are. If you had a complete map of the complete spectral sensitivity of each filter, you could probably generate a model of the camera's response well enough to create not-bad profiles from that information...but you'd need not just the spectral midpoint but enough other points on the curve to plot the entire thing. The green-filtered photosites are sensitive to red and to blue light, but not very sensitive. Knowing how sensitive they actually are would be essential to the type of modeling they're trying to make you think they're performing (and that perhaps they themselves even think they're performing), but you're not going to get that in any useful form from photographing the chart they're selling.

At best, they're well-intentioned but not very clueful. Maybe they're trying to reinvent the wheel without bothering with learning the fundamentals. Or maybe whoever is writing their marketing materials is clueless. Or maybe they're just blowing smoke up everybody's asses with technical-sounding bafflegab and a run-of-the-mill product.

Regardless, you've fell for their hype, hook, line, and sinker.

Considering that your knowledge of color science is so limited that you aren't aware of all the quantization and color shift and other problems associated with ProPhoto, it's not surprising that you'd be taken in by that kind of salesmanship. Color science is a deep and obscure field, and it's easy to get confused, which makes it even easier for people to intentionally or unknowingly confuse others, including for personal monetary gain.

But QPcard truly is, at best, a run-of-the-mill product. That the hype surrounding it makes it seem like the greatest thing since sliced bred when it truly isn't is enough reason to not give them any financial support by buying their products, even if they're truly sincere about the hype.

If you want a better color target than any you can buy today, it's not hard. Start with a classic ColorChecker; take it to your local paint store and have them match each of the colors. You might need to go to the newest paint store in town, as some of the colors are too saturated for those with older formulations to match. But the matches will be good spectral matches within the observed variation of the official targets over the years.

Next, go to your local art store and get a sample sheet / book / whatever of artist's paints. Golden Fluid Acrylics works well for this purpose, but they're hardly the only ones. Measure the samples with your spectrophotometer and pick a dozen or so samples with a representative mix of spectra. Buy those paints as well as a bit of white.

Now lay out your chart in Photoshop. You'll want the ColorChecker somewhere in the middle. You'll want each of your artist's paints in a few shades (mixed with white). You'll also want a number of patches that you'll print, including a dozen or so neutral patches as well as at least a hundred, preferably twice or more, patches distributed uniformly throughout perceptual space -- and, obviously, you'll need to have a good profile of the printer and paper you'll be using to generate that patch set. For bonus points, include a bit of PTFE thread tape for your whitest patch, a black trap (make the target a hollow black-lined box with a patch-sized hole for your darkest patch), and samples of real-world objects you'll care about (such as wood chips).

Print the target, paint in all the paints you've assembled, let it dry a day or three, measure the patches with your spectrophotometer, and build your profiles.

If your paint store will sell you pint-sized samples and if you're friendly with an artist who'll let you use her paints, you can build for yourself a color chart that puts everything on the market to shame for not much more than that QPcard will cost you...plus, of course, a significant investment in your own time....

trumpet Power, as usual you mix many things, and why are you writing so long text, no one can follow you, that the people behind qp-card dont know what they are doing, well that is sure a statement from your side.

who are you?

<sigh />

So sorry for confusing you with things like facts and details.

Let's try something simple.

That page you linked to has reference files for the QPcard.

Robin Myers did a superlative review of the ColorChecker Passport that you can read here:

He includes even more information about the Passport in his review than QPcard does on their Web page.

Compare the D50 Lab values for the two. Which chart has the most saturated colors?

Here -- I'll make it even easier for you.

The lower left patch on the QP203 is a saturated yellow. According to their reference file, it's L*=86.1, a*=5.2, b*=80.7. The ColorChecker Passport includes a similar yellow, third from the bottom on the leftmost column. According to Robin Myers (whose numbers very closely match my own measurements), it's D50 L*=87.02, A*=3.38, b*=86.80.

Which of those two colors is a more saturated, more pure yellow? Which is farthest from the neutral axis and closest to the spectrum locus?

That isn't a difficult or confusing or advanced or misleading or tricky question. It's not that different from asking which lens is faster or has the most reach.

If you know enough about color to answer those questions, we might be able to have a productive discussion. If not, kindly stop pretending you know so much about color -- and please stop pretending you know enough about color to evaluate the claims of the QPcard marketing department.

Viggo - I'm not sure it's very helpful but I use the color checker passport to get profiles for my 1dx and5d3. After carefully following the instructions lr4 produced some quite effective profiles for me. Certainly they are much better than the standard ones in lr or the "camera" options in lr. They aren't perfect, my red is oversaturated and I normally end up pulling it back a bit. But I have a good starting point if not a perfect one.

I paid close attention to getting the white balance right and the exposure. I seem to remember checking the exposure values of the whites and the color balance was specified in the instruction as needing to be within 1 percent.

Good luck hope it works out for you.

Logged

If you debate with a fool onlookers can find it VERY difficult to tell the difference.

It's also, incidentally, the answer for the rest of the saturated patches as well.

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and it has no meaning in terms of measurement

BZZZZT! Worng answer. Very, very, very, very worng answer.

Profiling is all about sampling the color space. The larger the sample space, the more sample points, and the greater the density around critical areas, the more the model can know about the behavior of the device. The more saturated the colors in the target (for those colors at the edge of the sample space), the larger the sample space and the less extrapolation the model needs to predict the response of even more saturated colors. Colors within the volume encompassed by the ColorChecker will be pretty accurately known but will have to be guessed at through extrapolation if you use the QPcard.

Indeed, there are people who are getting superlative profiling results using a tunable monochromatic light source and no lens -- and, obviously, not using traditional targets! (And, since I have no doubt but that you have no clue what that sentence means, it means that they're generating perfectly pure, perfectly saturated colors using some very expensive equipment and photographing the colors the instrument generates one at a time and building the profile from measurements of all the images of all the different purely saturated colors the instrument can produce.)

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have you tried if you get better accuracy with passport than with two yellow hues in op-card?

Why would I waste money on such a clearly inferior product sold by people whose marketing departments (and probably engineers) are clueless about color science?

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ps Lindbloom knows what this means, less metamerism errors

Thank you for demonstrating that you have no clue what "metamerism" means and its application to color profiling.

The only way that you could generically deal with metameric mismatches would be if you were capturing complete spectral information -- ideally of the metamers themselves, though you could fake it pretty well with a camera and a spectrometric recording of the illuminant.

Which is why it's not even pretended to be dealt with in ICC profiling. Instead, you just build a profile with an image of the target taken in the same illumination as you're shooting in. If the camera is reasonably close to satisfying the Luther Condition -- and all modern cameras are, though none (of course!) is perfect -- and your target is good enough (and neither the QPcard nor the Passport have nearly enough patches to really do this right, though the Passport is significantly better while still being inadequate) then the profiled image the camera makes will match the appearance of the metamer in that scene.

Can you then transform that image to simulate different viewing conditions? Of course not! Not without complete spectral readings and some very sophisticated math. There are folks at the Smithsonian who could do it, but not very many others.

However, with a well-profiled image, you can then make a print that, when viewed in standard conditions will match what the original scene looked like. And, if you can get a spectral reading of the original scene, you can make another, different print that will match the original scene when viewed in those conditions. But -- again of course -- since no printer uses (significantly) metameric inks (for very good reason!), you're obviously not going to get a single print that would match the original objet in any lighting.

Really, why it should even occur to you to bring metamerism into this is beyond me. Or did you just latch onto the first strange-sounding word you came across in a random Google search and hoped it'd somehow confound me and get me to stop pointing out your ignorance?

Congratulations! That's the correct answer. Who are you? start to study the subject then you understand why 2 different yellow hue is better than one, the time is now 00:59 and we can discuss this subject as much you want. keep your messages short and concise.and and stop being rude to people who have knowledge and requires three sentences instead of a bunch of bladder bludderTalk to Lindbloom as you referar to and you understand why there will be less errors

nighty nighty and cheers

Mikael, you are so hopeless I wonder why I bother.

First, you demonstrate the most appalling ignorance and incompetence. Then, when I and others correct the misinformation you spew, you never actually attempt to address any of the points I or anybody else makes, and instead you keep beating your same old tired Nikon DR / DxO / QPcard drums, always without content with any more depth than "two stops more physics better."

Who I am is utterly meaningless. Address my facts or not at all.

You'll notice that I'm not similarly challenging you, Mikael, to provide your own bona fides. Even if you've got a PhD in DxO, who you are is meaningless. It's your ideas that matter here, and your ideas suck almost as much as they're incoherent.

I've repeatedly explained in great detail why the gamut of the target is so important, even going so far as to include an example of somebody who uses a virtual target with the largest theoretically possible gamut. That you're suggesting that I haven't explained the importance of target gamut size -- that you're probably still not aware as you read these words that I just explained the importance of the choice of the yellow patches in question -- just goes to show that you're so far out of your league that you're the poster child for the Dunning-Kruger effect.

Really, this is every bit as bad as your attempts to "compare" dynamic range with an architectural shot completely devoid of detail because it was grossly unfocussed and shot at f/1.4, presumably hand-held. I keep trying to bring you up to speed on the most basic of matters, things that you absolutely must know to even be able to understand the discussion -- let alone contribute to it -- and all you can do is whine that I'm trying to tell you too much about things you don't understand.

I'm sure I've told you before about the First Rule of Holes. Your reputation here really couldn't possibly get worse, so even it might no longer apply...but, really. You're in the deepest hole I've ever seen an Internet troll work himself into, and yet you still keep digging as fast and furiously as you possibly can. Do you really think you're going to escape to China that way or something equally bizarre?

Viggo - I'm not sure it's very helpful but I use the color checker passport to get profiles for my 1dx and5d3. After carefully following the instructions lr4 produced some quite effective profiles for me. Certainly they are much better than the standard ones in lr or the "camera" options in lr. They aren't perfect, my red is oversaturated and I normally end up pulling it back a bit. But I have a good starting point if not a perfect one.

I paid close attention to getting the white balance right and the exposure. I seem to remember checking the exposure values of the whites and the color balance was specified in the instruction as needing to be within 1 percent.

Good luck hope it works out for you.

I think I must just suck it up and agree that I can't use it as a quick fix, but use it as a great starting point. If I just come to terms with that, and that is a lot easier now that I've read what TrumpetPower have written about the subject. It's not THAT much more work to post-tune the colors when the CC have made them, to me at least, way better.

I'm trying to find the Camera Calibration-profiles on my Mac with Mountain Lion OS. X-rite provides a path to the folder, but they aren't there, I enabled "Show hidden files" also, but they are no where to be found. Anybody who knows here?